Members of the Economic Community of West African States were called on by the U.N. Security Council to develop a plan for a neutral force for Mali.
Militant groups, some of which are aligned with al-Qaida, claimed autonomy for northern Mali following a series of political upheavals early this year. Some of the Islamic rebels there are accused of war crimes.
Ramtane Lamamra, peace and security commissioner for the African Union, was quoted by the BBC as saying his bloc supported a contingent backed by troops from Burkina Faso, Niger and Nigeria.
"This deployment aims to respond to the request by the Malian authorities to regain the occupied regions in the north of the country, dismantle the terrorist and criminal networks and restore effectively the authority of the state over the entire national territory," he said.
The French government, the former colonial power in Mali, said it would provide logistical and training support for the African mission.
The BBC notes that a military engagement in north Mali is expected to last several months, requiring support from concerned governments outside the region.
U.S. officials last month, in meetings in Algeria, stressed that a political process may need to work in parallel with military efforts in Mali.